Electrical musical instrument employing piano damper pedal operated switch



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Oct. 2, 1962 HANERT 3,056,328

J. M. ELECTRICAL MUSICAL INSTRUMENT EMPLOYING PIANO DAMPER PEDAL OPERATED SWITCH Filed Dec. 16, 1959 OP T E g ENVEL. E. CON KOL. TUB

ELECTRICAL FQAMPLIFIER & c BASS TONE 0 VOLUME CONTROL. GENERATOR L I as 27 UNITARY CONTROL. 5W\TcH OPERATED BY ANY PEDAL.

XXXIIIAIXIKXI Xx. xlnnulrlr Iv, yxinlvlinxx W XMM. rh me/L5 United States Patent Ofilice Patented Oct. 2, 1962 Ware Filed Dec. 16, lass, Ser. No. 859,984 6 Qlaims. c1. 84-417) My invention relates generally to electrical musical instruments and more particularly to an instrument to be played with a piano to supply the bass tones, and which is in part controlled by the operation of the damper or sustaining pedal of the piano with which it is used.

In instruments of the type shown in Hammond et al., Patent No. 2,480,132, it is desirable to have the tones produced by the electrical instrument sound with a sustained intensity envelope whenever the piano sustaining pedal is depressed, and to have a rather short decay time when the sustaining pedal is released to apply the dampers to the piano strings.

In said patent it was contemplated that an auxiliary switch for such envelope control of the electrical musical instrument would be placed beneath the piano sustaining pedal and operated thereby. However, I have found that there is a considerable variation among pianos of dilferent makes with respect to the dimensions, shape, and unevenness in the under surfaces of the sustaining pedal as well as its spacing from the floor. Furthermore, I have found that, after becoming acquainted with a particular piano, the pianist tends to only partially release the damper pedal in his playing, thus reducing the pedals usable travel for reliable operation of an auxiliary switch. In other words, the pianist soon learns to release the pedal to a degree which is no more than is necessary to damp the strings. This imposes a stringent requirement of precise operation of the auxiliary switch with respect to the piano dampers, and I have found it diificult to meet this synchronization requirement in a practical manner with the auxiliary switch shown in said patent.

The present invention is directed to overcoming this diiiiculty and providing a very simple and low cost switch which is operated in a very precise and reliable manner by the piano sustaining pedal. The switch is normally not visible and its installation does not detract from the appearance of the piano. Another advantage of this switch which was not enjoyed by the switch shown in said patent is that the switch is actually integral with the piano, and the cable to it may be readily disconnected from a plug and receptacle box when it is desired to move the piano.

The switch shown in said patent, however, was intended to be guided, spaced, and adjusted relative to the floor on which the piano was standing. In the event that the piano was to be moved, it was necessary first to remove the switch, move the piano, and then reassemble the switch and readjust its operation precisely and carefully relative to the operation of the piano dampers. This readjustment posed a practical problem where a piano is to be rapidly moved on and off of a stage in a school auditorium, for example. The present invention overcomes this problem very satisfactorily.

It is therefore the primary object of the invention to provide an improved switch means for operation by the sustaining pedal of a piano and which utilizes parts normally present in all makes of pianos as parts of the switch.

Another object of the invention is to provide a novel form of electrical switch which is wiped clean many times a second because of sympathetic vibrations of a piano string.

Another object of the invention is to provide an electrical damper switch for an electrical bass tone musical 2 instrument whose operation is accurately synchronized with the opening and closing of the piano damper felts relative to the strings.

Other objects will appear from the following description reference being had to the accompanying drawings in which:

FIG. 1 is a side elevational view, partly in section, showing portions of a conventional piano key action with a portion of one of the strings, and representative block and schematic wiring diagram; and

FIG. 2 is a perspective view of the damper block.

To accomplish the above objects the damper head and string are utilized as contact parts of a switch. As shown, the damper Til, which has a felt head pad ill cemented thereto, has a wire 12 wound around it and around a screw is threaded in the damper head. The damper It is operable through the usual piano action by piano key 16, or by a damper, sustaining, or sostenuto pedal 18. Thus, when the key 16 is depressed the hammer 20 is swung to strike a string 22 while at the same time the damper head it is moved away from the string. As is well known, depression of the pedal 18 causes all of the damper heads to be moved away from their associated strings.

A second wire 24 is wound around the metallic tuning pin 26 used to apply tension to the string 22. The wires 12 and 24 are connected to a detachable plug and socket connector 28 and are thus connected respectively to a conductor 3d and a grounded conductor 32. it will thus be apparent that when the damper head 11 is pressed against the string a circuit will be completed between conductor 3t and ground which connection will be broken when either of the piano key M or the pedal 18 is depressed.

The instrument is played by means of a pedalboard 33 having a plurality of pedals 34. The pedals operate switches which operate to tune an electrical bass tone signal generator 36 to the selected pitch. The connection between the pedalboard 33 and generator 36 is through a multi-conductor cable 38. In addition to operating switches to tune the generator 36 to a frequency corresponding to the pitch represented by a depressed pedal, each of the pedals, when depressed, operates to move switch arms 40 and 41 from full line to the dotted line position.

The output of the generator 36 is supplied through a capacitor C42 to the control grid 44 of an intensity envelope control tube 46, shown as a pentode of the variable mu type. The suppressor grid 48 and cathode 50 are connected to ground through an adjustable resistor R52, while the screen grid is maintained at suitable operating potential by a voltage divider comprising resistors R54 and R55 which are connected in series between the cathode 5d and a source of 13+ potential indicated as a +290 v. terminal of a suitable power supply. The plate 56 of this tube is also connected to said terminal through a plate load resistor Rdtl and is coupled through capacitor C61 to a suitable amplifier 62., which may include a suitable volume control. The output of the amplifier is coupled to a speaker 6 1'.

The pentode 46 is normally biased beyond cutoff by virtue of the fact that its control grid 44 is connected to ground through resistors R66 and R68 and because the cathode 50 is maintained at a potential positive with respect to ground due to the voltage dividing effect of resistors R52, R54, R55, and cathode connected resistor R70, normally closed switch 46, and resistor R72 which is connected to ground. This resistor has a capacitor C74 connected in parallel therewith. The control grid 44 is also connected to ground through resistors R66 and R76, the normally closed switch 41, conductor 36, wire 12, piano string 22, and conductors 2d and 32. The

"9 value of resistor R76 is low relative to that of resistor R68 so that it, together with resistor R66, constitutes a low resistance path connecting the control grid to ground.

When any of the pedals 34 is depressed the switch 40-, in moving from full to dotted line position, connects the ungrounded terminal of capacitor C74 through an antispark and attack rate resistor R30 to grid resistor R65, and the potential of the grid is raised to full operating potential. At the same time, the grid is disconnected from the low resistance path to ground by the opening of the switch 41. The charge on capacitor C74 is also, in part, transferred to a capacitor C82 which is in parallel with resistor R68. The rate of charging the capacitor CS2 by the transfer of a charge from capacitor C74 is preferably relatively rapid but not sufliciently rapid to cause an undesirable transient at the instant the pentode 46 is rendered conducting. The capacitor C82 is of sufficient value that if the pedal 34 is held depressed the decay portion of the tone intensity envelope will extend over a considerable period, as the charge on the capacitor C82 is dissipated through resistors R89, switch 40, and resistor R72. This decay time may approximate that of the low pitched piano strings.

Upon release of the pedal 34 and consequent movement of switches 46 and 41 to full line position any remaining charge on capacitor C82 is rapidly discharged through the low resistance path comprising resistors R76, switch 41, and the switch formed by conductors l2 and the piano string 22 and conductors 24 and 32. If, however, the sustaining pedal 18 is depressed to raise the damper head from the string 22 of low resistance discharge path for the capacitor C82 is open and as a result the capacitor can discharge only through resistor R68, which is of sufiiciently high value that the tone produced by the speaker 64 will decay at approximately the same rate as the piano tones decay when the sustaining pedal is depressed.

The switch formed by the damper head 10, wire 12, and piano string 22 is of minimum cost, is normally not visible and thus does not detract from the appearance of the piano, and is very reliable in its operation. The electrical musical instrument is readily disconnected from the piano by disengaging the plug and socket 28, for ease in transportation permitting use of the piano in the usual manner.

While I have shown and described a particular embodiment of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof, without departing from the more fundamental principles of the invention. I therefore desire, by the following claims, to include within the scope of my invention all such similar and modified forms of the apparatus d'isclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

I claim:

1. For use in conjunction with an electrical musical instrument to be played with a piano and in which the instrument has tone intensity envelope control circuitry which requires the operation of a switch incidental to the depression and release of the sustaining pedal of the piano and in which the piano has a damper operable by the sustaining pedal and cooperable with a string to damp the vibration thereof, electrically conducting means applied to a damper block of the piano at the surface which normally contacts its associated string, and conductors forming part of the control circuit for the tone intensity envelope control means and respectively connected to the conducting means of the damper block and to its associated string.

2. A switch for use with a piano for the control of the intensity envelope of the tones produced by an electrical musical instrument to be played with the piano, comprising, a conductor on a damper block of the piano and normally pressed against its associated string, and a conductor electrically connected to the associated string.

3. A piano switch for the control of the intensity envelope of the tones produced by an electrical musical instrument to be played in accompaniment with the piano, said piano having strings and damper members for said strings, comprising a switch contact fixed to move with one of the damper members of the piano and a second switch contact fixed with respect to the position of the piano string associated with said damper member, said contacts being adapted mutually to engage when said damper member is against said string and to separate when said damper member moves away from said string.

4. In musical apparatus of the type in which a piano includes tone producing strings and movable damper members engaging the strings in one position thereof and in which an electrical musical instrument adapted to be played in accompaniment with the piano includes a tone intensity envelope control circuit, in combination with the strings, the damper members and the control circuit, first electrically conductive material associated with the damper members, second electrically conductive material associated with the strings and engaged by the first electrically conductive material in said one position of the damper members, and a circuit including the first and second electrically conductive material controlling the tone intensity envelope control circuit.

5. In musical apparatus of the type in which a piano includes tone producing metallic strings and movable damper members each engaging a respective string in one position thereof and in which an electrical musical instrument adapted to be played in accompaniment with the piano includes a tone intensity envelope control circuit, in combination with the strings, the damper members and the control circuit, electrically conductive elements carried by the damper members each engaging the respective string in said one position of its damper member, and a circuit including the strings and the electrically conductive elements controlling the tone intensity envelope control circuit.

6. In musical apparatus of the type in which a piano includes a tone producing string and a movable damper member engaging the string in one position thereof and in which an electrical musical instrument adapted to be played in accompaniment with the piano includes a tone intensity envelope control circuit, in combination with the string, the damper member and the control circuit, an electrically conductive element carried by the damper member engaging the string in said one position of the damper member, and a circuit including the string and the element controlling the tone intensity envelope control circuit.

References Cited in the file of this patent UNITED STATES PATENTS 

